1. Field of the Invention
The present invention relates a vehicle seat for a child generally referred to as a child seat and, in particular, to a child seat which can be set at a desired angle regardless of the angles of a vehicle seat.
2. Description of the Related Art
when loading a baby or a little child into a vehicle, sometimes a child Seat is used in order to secure the safety of the baby or child in an emergency such as when applying the brake suddenly. While child seats vary widely in structure, description will be given below of an example of them.
Generally, a child seat 111, as shown in FIG. 23, includes a seat main body 113 in which a baby or a little child 112 is seated, a receiver base 114 which supports the seat main body 113 in such a manner that the seat main body 113 can be rotated freely between a forward facing position and a backward facing position with respect to the advancing direction of the vehicle or the angle of the seat main body 113 can be adjusted freely (that is, the seat main body 113 can be reclined freely), and the like. And, when fixing the child seat 111 to a vehicle seat 115, receiver base 114 is fixed to the vehicle seat 115 by a vehicle seat belt (not shown) or the like.
Especially, for a baby underdeveloped in body, the child seat is mounted backward with respect to the vehicle advancing direction before it is used, in order to hold the baby body through the whole of the back of the baby. On the other hand, for a child developed in body to a certain degree, the child seat is mounted forward with respect to the vehicle advancing direction in order to hold the body of the child through the lower back, abdomen, breast of the child body while the child is seated.
By the way, there is a safety standard for the child seat 111 and, in compliance with the safety standard, a. collision test is conducted o the child seat 111 under the condition of a test seat having a o at surface elevation angle of 3.degree., as shown in FIG. 23 (its forward facing position) and in FIG. 25 (its backward facing position).
Thus, the angle of the seat main body 113 of the child seat 111 (which includes its inherent angle a and a proper reclining angle b) is set in consideration of the safety and comfort of the little child 112 under the above-mentioned safety standard of the a test seat having a seat surface elevation angle of 3.degree..
However, the elevation angles of the vehicle seats 115 actually on the market are not always set at the angle of 3.degree. in all vehicles but, as shown in FIG. 24, there are found many vehicles in which the vehicle seats thereof are set about at 15.degree.; that is, in fact, the elevation angles of the vehicle seats vary widely. Thus, in FIG. 23 showing the vehicle seat having an elevation angle of 3.degree., when an operator is going to set the reclining angle for the angle a and thus to use the child seat 111 in the most-raised position, in actual use, an shown in FIG. 24, the child seat 111 lies on its back side by an excess angle corresponding to the increased angle of the elevation angle of the vehicle seat, that is, by 12.degree.. On the other hand, in FIG. 23 showing the vehicle seat having an elevation angle of 3.degree., when the operator is going to set the reclining angle for the angle b and thus to use the child seat 111 in the most-lowered position, in the vehicle seat having an elevation angle of 15.degree. shown in FIG. 24, the child seat 111 lies on its back side further by 12.degree., that is, by the increased angle of the elevation angle of the vehicle seat, with the result that the child seat 111 lies on its back side far beyond the reclining angle b that is set as the most proper angle when the child 111 seat is designed.
In this manner, in the conventional child seat, even if the proper reclining range or angle b is taken into consideration when the child seat is designed, actually, in many cases, the comfort of the child seat cannot be secured.
The above fact also applies similarly to a case shown in FIG. 25 in which the child seat 111 is set backward with respect to the advancing direction of the vehicle. That is, in FIG. 25 showing a vehicle seat having an elevation angle of 3.degree., normally, the angle of the child seat is set with some room, in particular, for an angle of the order of 50.degree. in the range of the safety standard (the safety standard angle ranges from the vertical direction to an angle of 60.degree.), because a baby who cannot yet hold its head up should be laid down as deep as possible. However, if the child seat 111 is used when the vehicle seat 115 has an elevation angle 15.degree. as shown in FIG. 25, in fact, the child seat 111 is raised up by an angle of 12.degree. corresponding to an increase in the elevation angle although the operator is going to use the child seat 111 in its most-lowered position, which brings the child seat 111 to a state not desirable for the baby who cannot hold its head up.
On the other hand, in the conventional child seats, there are found child seats structured such that the reclining angle thereof can be adjusted in a wide range and, if such child seat is used, it is truly possible to absorb the elevation angle difference between the child seat and vehicle seat. But, when such child seat capable of adjusting the reclining angle in a wide range is used, if the child seat is used backward with respect to the vehicle advancing direction, then, each time the reclining angle is changed, there arises the need to confirm whether the reclining angle after changed is in the range of the safety standard or not, which is troublesome or inconvenient. In addition to this, if the operator should fail to confirm this, not only the comfort of the baby is disturbed but also, when the child seat is lied on its back side beyond the angle of 60.degree. from the vertical direction, in sudden braking or in a collision, there is a danger that the baby can be flown out from the child seat because the reclining angle is not proper.
Also, as means which, each time the reclining angle is changed, confirms whether the angle after changed is in the range of the safety standard or not, there is disclosed a vehicle seat level display device Unexamined in Japanese Patent Publication Hei. 8-20250(PCT/US 91/06419), which displays whether a child seat is set in a proper position or not.
However, since the vehicle seat level display device is not able to make angle adjustments between the child seat and the vehicle seat onto which the child seat is to be mounted, similarly to the previously described case, there arises the need to confirm the angles of the child seat and vehicle seat each time the child seat is mounted.